For certain applications in chemical lasers, there is a need for optical resonators which have different magnifications (and other properties) along orthogonal (x and y) axes perpendicular to the propagation direction. For example, there is such a need in connection with high-energy chemical lasers in which the gain region is much shorter along the x-axis (flow direction) than along the y-axis. Such asymmetric-magnification resonators may be constructed with non-spherical mirrors, but acceptable non-spherical mirrors are much more difficult to fabricate than mirrors with a spherical configuration. Also, the use of spherical mirrors in conventional orientation such as in the confocal unstable resonator, requires the mirror normal to be along (or nearly parallel to) the propagation direction. A resonator of this type has larger diffraction spillage losses in the short or x direction. Therefore, there is a need for an optical resonator with simple mirror arrangements which overcome difficulties encountered in previous resonator schemes.
Accordingly, it is an object of this invention to provide tilted spherical mirror resonator arrangements which have means for varying the resonator mode volume and asymmetric magnification in a continuous fashion to match the chemical gain medium and thereby maximize laser extraction efficiency.
Another object of this invention, is to provide asymmetric-magnification resonators which are fabricated using spherical mirrors and roof top mirrors and avoiding non-spherical mirror arrangements. A further object of this invention is to provide spherical-mirror resonators which achieve desired asymmetric-magnification by utilizing configurations such that the normal to the spherical-mirror surfaces are rotated through rather large angles with respect to conventional orientation in which mirror normals are parallel or substantially parallel to the propagation direction.
A still further object of this invention is to provide a ring resonator that utilizes tilted spherical-mirror surfaces.
Other objects and advantages of this invention will be obvious to those skilled in this art.